Is It On KEV?

Microsoft Defender

YES - ON THE CISA KEV LIST
CVE-2021-1647

Microsoft Defender Remote Code Execution Vulnerability

CISA catalog due date2021-11-17
overdue since 2021-11-17
EPSS exploit probability (next 30 days)39.7% · 99percentile
From CVE publication to KEV listing295 days (2021-01-12 → 2021-11-03)
Remediation window (KEV listing to due date)14 days
Days on the KEV list1834 days
Date added to KEV2021-11-03
Known ransomware campaign useUnknown
VendorMicrosoft
ProductDefender
Weaknesses (CWE)CWE-122, CWE-1285

Microsoft: 391 entries (22.0% of all KEV entries are from this vendor); 41 added in 2026.

BOD 26-04 note: this is the date printed in the CISA catalog. A federal agency's actual deadline is set by its SSVC tier - Act (3 days), Attend (14 days), Track (60 days), or the next scheduled upgrade - counted from the KEV listing date or the date the vulnerability is identified in its environment, whichever comes first. Use the tier helper on each CVE page for your own window.

Your BOD 26-04 window (SSVC tier helper)

Your remediation window ends:

Description

Microsoft Defender contains an unspecified vulnerability that allows for remote code execution.

Required action (CISA)

Apply updates per vendor instructions.

Notes

https://nvd.nist.gov/vuln/detail/CVE-2021-1647

References

Other KEV entries for this vendor: Microsoft

Microsoft - Vendors with KEV entries

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